what happens after ddr island with the guy does he eventually do something interesting besides tell you to go places?

I don't think so. Quest mode is just like a work out. You can dance to as many songs in an area as you want. You could go anywhere you want I guess.

Here's what happens: Baldo gives you a very special trophy and will become your manager for 5000 points.

Hint on beating DDR Island: Get Star as your promoter, then it comes down to getting lucky on songs. If you can get the right songs on Heavy and fill your gauge up in at least 2 songs, you can do it. I know this because I just did that. (With a little help from someone who I will keep anonymous, except to say I talked to him via email the other day. He was the programmer of Quest Mode...if he's reading this, thanks a lot, buddy. I really owe you one).